In recent years, analysis methods for searching for biological phenomena not appearing in the appearance have attracted attention, by comprehensively analyzing relative variations of metabolites contained in living bodies. This analysis method is called metabolome analysis and the like, and is attempted to be applied in a medical field such as diagnosis of disease and analysis of etiology, a medicine field such as toxicity of pharmaceuticals and the like or side effect test. In addition to the field related to medicine, application is also expected in fields such as food quality control, quality appraisal, quality prediction, food safety assessment, food production optimization, and breeding of industrial microorganisms, plants and the like.
As described above, in the metabolome analysis, for example, in order to analyze a relative variation of a substance to be analyzed or the like, it is necessary to perform a pretreatment of a sample to be analyzed, measure the substance to be analyzed using the analytical sample obtained by the pretreatment, and perform analysis based on the measurement result. In this case, a gas chromatography mass spectrometer, a liquid chromatography mass spectrometer or the like is generally used as an apparatus for measuring the substance to be analyzed. On the other hand, a sample derived from a living body such as human or a sample derived from food contains a large number of components in various concentration ranges. However, the concentration range measurable by one treatment in an analyzer such as a gas chromatograph is limited. For example, a low concentration component is in a measurable range, but a component at high concentration exceeds the measurable range. Thus it is impossible to obtain the measurement result of the necessary component in one measurement with respect to one sample, and it is necessary to perform measurement twice or more. In addition, when components at high concentration in which the retention times of the chromatograph are close to each other exist in large number, it becomes difficult to detect or quantify the peak of a component at low concentration in which the retention time is close to them, and it becomes difficult to analyze the component at low concentration. Furthermore, for example, when a large amount of high concentration components are introduced into a separation column such as a gas chromatograph, the retainable capacity of the liquid phase of the separation column is exceeded. This causes the retention time including those for the target components sometimes largely shifts. When the retention time shifts, analysis becomes difficult. Especially when measuring multiple components like metabolome analysis, analysis is hindered.
In response to such a situation, a chromatograph which makes it possible to measure a wide range of components from high concentration components to low concentration components has been proposed. For example, Patent Literature 1 has proposed a gas chromatograph that is equipped with a sample valve, a measuring tube, a column, and a detector, and includes four valves. The four valves are: a stop valve; a pressure reducing valve; and a three-way valve alternately introducing a sample gas and a standard gas, which are arranged in this order from the sample valve side in an inflow passage of the sample gas; and a stop valve which is arranged in a discharge passage of the sample gas. The gas chromatograph also includes a calculation section for controlling these four valves. In this gas chromatograph, it is considered that a wide range of components can be measured by having configuration in which the sample amount increases or decreases regardless of the size of the measuring tube.
Further, as a method of detecting a peak by adjusting a retention time in a chromatograph, it has been proposed to change the concentration of the elution solvent, for example, in separation and elution of the analyte by liquid chromatography. For example, Patent Literature 2 discloses, as a method of analyzing an amino-functional compound liquid containing various kinds of amino acids and derivatives thereof contained in a living body and amino acid analogous substances, a method of analyzing an amino-functional compound. The method includes steps of reacting an amino-functional compound in a sample containing the amino-functional compound with a derivatization reagent to produce a predetermined amino-functional compound derivative, eluting the amino-functional compound derivative by liquid chromatography using a stepwise concentration gradient elution means, and detecting, by mass spectrometry, the amino-functional compound derivative eluted by the liquid chromatography.